The role overriding mandatory rules play in arbitration has very significant practical implications, up to and including the survival of arbitration as an instrument for dispute settlement in international commercial relations. Indeed, a perception that such rules are not taken into due consideration by arbitrators could lead to a change in the liberal and positive attitude of States and their courts towards arbitration. As is well known, in the last decades States have accepted and even encouraged arbitration, manifesting a liberal attitude toward arbitrability and the review of awards at the setting aside and enforcement stages. Ever since the US Supreme Court’s decision in Mitsubishi v. Soler-Plymouth, which for the first time accepted the arbitrability of overriding mandatory rules (in that case in the context of competition law), States have displayed confidence in arbitration, specifically trusting that arbitrators would apply overriding mandatory rules when the dispute brought to arbitration fell within their scope. At a time when the role of arbitration is increasingly under scrutiny, questioned, and partially misunderstood (most worryingly by the institutions of the EU), it is crucial that the role of overriding mandatory rules and the principles governing their proper application should be well understood.
The topic also raises interesting theoretical issues, because it requires an exploration of the mechanisms that preside over the application of substantive rules in international arbitration. Although much has been written on the subject, several areas of uncertainty remain which warrant further investigation.